Optical layered body

ABSTRACT

Provided is an optical laminate having the following feature: when the optical laminate is used in an image display apparatus, the optical laminate can express a sufficient brightness, can express a satisfactory hue, and can achieve a cost reduction while suppressing a reflectance. The optical laminate of the present invention includes: a wavelength conversion layer; and an absorption layer arranged on one side of the wavelength conversion layer, wherein the absorption layer has an absorption peak in a wavelength band in a range of from 580 nm to 610 nm, and wherein the absorption layer contains a compound x represented by the general formula (I) or the general formula (II).

TECHNICAL FIELD

The present invention relates to an optical laminate.

BACKGROUND ART

In recent years, an image display apparatus including a light-emittinglayer including a light-emitting material, such as quantum dots, hasbeen attracting attention as an image display apparatus excellent incolor reproducibility (e.g., Patent Literature 1). For example, whenlight enters a quantum dot film using quantum dots, the quantum dots areexcited to emit fluorescence. For example, when the backlight of a blueLED is used, part of blue light is converted into red light and greenlight by the quantum dot film, and another part of the blue light isoutput as it is as blue light. As a result, white light can be achieved.Further, the use of such quantum dot film is said to be capable ofachieving a color reproducibility of 100% or more in terms of NTSCratio.

Such image display apparatus as described above has a high reflectance.In view of the foregoing, a polarizing plate is generally used in suchimage display apparatus as described above for reducing the reflectance.

However, the use of the polarizing plate involves a problem, such as areduction in brightness of the apparatus, an abnormal hue thereof, or anincrease in cost thereof. Accordingly, a brightness improvement, a hueimprovement, and a cost reduction have been required in such imagedisplay apparatus as described above.

CITATION LIST Patent Literature

[PTL 1] JP 2015-111518 A

SUMMARY OF INVENTION Technical Problem

The present invention has been made to solve the conventional problems,and a primary object of the present invention is to provide an opticallaminate having the following feature: when the optical laminate is usedin an image display apparatus, the optical laminate can express asufficient brightness, can express a satisfactory hue, and can achieve acost reduction while suppressing a reflectance.

Solution to Problem

According to one embodiment of the present invention, there is providedan optical laminate, including: a wavelength conversion layer; and anabsorption layer arranged on one side of the wavelength conversionlayer, wherein the absorption layer has an absorption peak in awavelength band in a range of from 580 nm to 610 nm, and wherein theabsorption layer contains a compound X represented by the followinggeneral formula (I) or general formula (II).

in the formula (I),

R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, a substituted or unsubstituted alkylgroup having 1 or more and 20 or less carbon atoms, a substituentrepresented by the formula (a), or a substituent represented by theformula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₅ and R₆ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₁, R₂, R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₆ and R₇ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₂, R₃, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, R₅ and R₆ form a saturated cyclic skeleton including 5 or 6carbon atoms, and R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b), or

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, R₆ and R₇ form a saturated cyclic skeleton including 5 to 7carbon atoms, and R₁, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b); and

in the formula (II), R₄ and R₈ each independently represent a hydrogenatom, or a substituted or unsubstituted alkyl group having 1 or more and20 or less carbon atoms.

In one embodiment, the optical laminate is free of a polarizing plate ona side of the absorption layer opposite to the wavelength conversionlayer.

In one embodiment, the wavelength conversion layer contains quantum dotsor a phosphor as a wavelength conversion material.

In one embodiment, the wavelength conversion layer is a color filter.

According to another embodiment of the present invention, there isprovided an image display apparatus. The image display apparatusincludes the optical laminate.

In one embodiment, the image display apparatus includes a liquid crystalpanel including the optical laminate, and a backlight.

In one embodiment, the liquid crystal panel includes the absorptionlayer, the wavelength conversion layer, a viewer-side polarizing plate,a liquid crystal cell, and a backlight-side polarizing plate in thestated order from a viewer side.

Advantageous Effects of Invention

According to the present invention, the optical laminate having thefollowing feature can be provided: when the optical laminate is used inan image display apparatus, the optical laminate can express asufficient brightness, can express a satisfactory hue, and can achieve acost reduction while suppressing a reflectance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of an optical laminate according toone embodiment of the present invention.

FIG. 2 is a schematic sectional view of one embodiment of an imagedisplay apparatus including the optical laminate of the presentinvention.

FIG. 3 is a schematic sectional view of an optical laminate according toone embodiment of the present invention.

FIG. 4 is a schematic sectional view of one embodiment of an imagedisplay apparatus including the optical laminate of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Now, preferred embodiments of the present invention are described.However, the present invention is not limited to these embodiments.

<<<<Optical Laminate>>>>

FIG. 1 is a schematic sectional view of an optical laminate according toone embodiment of the present invention. An optical laminate 100 of thisembodiment includes a wavelength conversion layer 10 and an absorptionlayer 20 arranged on one side of the wavelength conversion layer 10. Inone embodiment, the optical laminate 100 is arranged on the viewer sideof an image display apparatus so that the absorption layer 20 maybe onthe viewer side.

The wavelength conversion layer is a layer configured to convert thewavelength of part of incident light to emit light.

The absorption layer contains a specific coloring matter to be describedlater (coloring matter represented by the general formula (I) or (II)).When the absorption layer is formed so as to contain such specificcoloring matter, an optical laminate having the following feature can beprovided: when the optical laminate is used in an image displayapparatus, the optical laminate can express a sufficient brightness, canexpress a satisfactory hue, and can achieve a cost reduction whilesuppressing a reflectance.

In one embodiment, the optical laminate is free of a polarizing plate onthe side of the absorption layer opposite to the wavelength conversionlayer. Even when the optical laminate of the present invention does notinclude any polarizing plate, the optical laminate can express asufficient brightness and can express a satisfactory hue whilesuppressing a reflectance. In addition, the exclusion of a polarizingplate can prevent a brightness reduction and achieve a cost reduction.Further, the mechanical characteristics of the absorption layer can beadjusted with a high degree of freedom, and hence, for example, suchdesign that a function as a hard coat layer is imparted to the layer inaddition to a reflection-reducing function is possible. Such a mode that“the optical laminate is free of a polarizing plate on the side of theabsorption layer opposite to the wavelength conversion layer” as usedherein includes such a mode that the optical laminate is free of apolarizer at the site, and such a mode that the optical laminate is freeof a circularly polarizing plate at the site.

The thickness of the optical laminate of the present invention ispreferably from 10 μm to 1,000 μm, more preferably from 15 μm to 800 μm,still more preferably from 20 μm to 600 μm, particularly preferably from20 μm to 500 μm.

The total light reflectance of the optical laminate (a measurementmethod therefor is described in detail later) is preferably 60% or less,more preferably 50% or less, still more preferably 40% or less,particularly preferably 35% or less, most preferably 30% or less. Thelower limit value of the total light reflectance of the opticallaminate, which is desirably as small as possible, is, for example, 5%.

In the present invention, a Δab based on the reflection hue (a*, b*) ofthe optical laminate (a measurement method therefor is described indetail later) with respect to a D65 light source is preferably 8 orless, more preferably 7 or less, still more preferably 6 or less. Thelower limit value of the Δab is desirably as small as possible, and isideally 0. When the Δab of the optical laminate of the present inventionfalls within the ranges, the optical laminate can express a moresatisfactory hue in the case of being used in an image displayapparatus. The Δab is determined from the equation“Δab=(a*²+b*²)^(1/2)”.

The optical laminate of the present invention may include anyappropriate other layer to the extent that the effect of the presentinvention is not impaired.

The optical laminate of the present invention may include a protectivefilm. Specifically, the optical laminate of the present invention mayinclude the protective film on, for example, the side of the absorptionlayer opposite to the wavelength conversion layer.

The optical laminate of the present invention may include a refractiveindex-adjusting layer. Specifically, the optical laminate of the presentinvention may include the refractive index-adjusting layer on, forexample, the side of the absorption layer opposite to the wavelengthconversion layer.

<<Wavelength Conversion Layer>>

The wavelength conversion layer typically contains a wavelengthconversion material. More specifically, the wavelength conversion layermay contain a matrix and a wavelength conversion material dispersed inthe matrix.

The wavelength conversion layer may be adopted as, for example, a colorfilter.

The wavelength conversion layer may be a single layer, or may have alaminated structure. When the wavelength conversion layer has alaminated structure, its respective layers may typically containwavelength conversion materials having different light emissioncharacteristics.

The thickness of the wavelength conversion layer (when the layer has alaminated structure, its total thickness) is preferably from 1 μm to 500μm, more preferably from 100 μm to 400 μm. When the thickness of thewavelength conversion layer falls within such ranges, an opticallaminate excellent in conversion efficiency and durability can beobtained. When the wavelength conversion layer has a laminatedstructure, the thickness of each of its layers is preferably from 1 μmto 300 μm, more preferably from 10 μm to 250 μm.

<Matrix>

Any appropriate material maybe used as a material for forming the matrix(hereinafter sometimes referred to as “matrix material”) to the extentthat the effect of the present invention is not impaired. Examples ofsuch material include a resin, an organic oxide, and an inorganic oxide.It is preferred that the matrix material have low oxygen permeabilityand low moisture permeability, have high light stability and highchemical stability, have a predetermined refractive index, haveexcellent transparency, and/or have excellent dispersibility for thewavelength conversion material. The matrix may practically include aresin film or a pressure-sensitive adhesive.

(Resin Film)

When the matrix is a resin film, any appropriate resin may be used as aresin for forming the resin film to the extent that the effect of thepresent invention is not impaired. Specifically, the resin may be athermoplastic resin, maybe a thermosetting resin, or may be an activeenergy ray-curable resin. Examples of the active energy ray-curableresin include an electron beam-curable resin, a UV-curable resin, and avisible light-curable resin.

When the matrix is a resin film, specific examples of the resin forforming the resin film include epoxy, (meth)acrylates (e.g., methylmethacrylate and butyl acrylate), norbornene, polyethylene, poly(vinylbutyral), poly(vinyl acetate), polyurea, polyurethane, aminosilicone(AMS), polyphenylmethylsiloxane, polyphenylalkylsiloxanes,polydiphenylsiloxane, polydialkylsiloxanes, silsesquioxanes, siliconefluoride, vinyl and hydride-substituted silicones, styrene-basedpolymers (e.g., polystyrene, aminopolystyrene (APS), poly(acrylonitrileethylene styrene) (AES)), polymers each cross-linked with a difunctionalmonomer (e.g., divinylbenzene), polyester-based polymers (e.g.,polyethylene terephthalate), cellulose-based polymers (e.g., triacetylcellulose), vinyl chloride-based polymers, amide-based polymers,imide-based polymers, vinyl alcohol-based polymers, epoxy-basedpolymers, silicone-based polymers, and acrylic urethane-based polymers.Those resins may be used alone or in combination thereof (e.g., blend orcopolymer). After any one of those resins has been formed into a film,the film may be subjected to a treatment, such as stretching, heating,or pressurization. The resin is preferably a thermosetting resin or aUV-curable resin, more preferably a thermosetting resin.

(Pressure-Sensitive Adhesive)

When the matrix is a pressure-sensitive adhesive, any appropriatepressure-sensitive adhesive may be used as the pressure-sensitiveadhesive to the extent that the effect of the present invention is notimpaired. The pressure-sensitive adhesive preferably has transparencyand optical isotropy. Specific examples of the pressure-sensitiveadhesive include a rubber-based pressure-sensitive adhesive, an acrylicpressure-sensitive adhesive, a silicone-based pressure-sensitiveadhesive, an epoxy-based pressure-sensitive adhesive, and acellulose-based pressure-sensitive adhesive. The pressure-sensitiveadhesive is preferably a rubber-based pressure-sensitive adhesive or anacrylic pressure-sensitive adhesive.

<Wavelength Conversion Material>

The wavelength conversion material can control the wavelength conversioncharacteristic of the wavelength conversion layer. Examples of thewavelength conversion material include quantum dots and a phosphor. Thatis, the wavelength conversion layer preferably contains quantum dots ora phosphor as the wavelength conversion material.

The content of the wavelength conversion material in the wavelengthconversion layer (when two or more kinds of materials are used, theirtotal content) is preferably from 0.01 part by weight to 50 parts byweight, more preferably from 0.01 part by weight to 30 parts by weightwith respect to 100 parts by weight of the matrix material (typically aresin or pressure-sensitive adhesive solid content). When the content ofthe wavelength conversion material falls within such ranges, an imagedisplay apparatus excellent in balance among all of R, G, and B hues canbe achieved.

(Quantum Dots)

The center emission wavelength of each of the quantum dots may beadjusted by, for example, a material for the quantum dots, and/or thecomposition, particle size, or shape of each of the dots.

The quantum dots may each include any appropriate material to the extentthat the effect of the present invention is not impaired. The quantumdots may each include preferably an inorganic material, more preferablyan inorganic conductive material or an inorganic semiconductor material.Examples of the semiconductor material include Group II-VI, Group III-V,Group IV-VI, and Group IV semiconductors. Specific examples thereofinclude Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs,AIN, Alp, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, ZnO,ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe,BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe,CuF, CuCl, CuBr, CuI, Si₃N₄, Ge₃N₄, Al₂O₃, (Al,Ga,In)₂(S,Se,Te)₃, andAl₂CO. Those materials may be used alone or in combination thereof. Thequantum dots may each contain a p-type dopant or an n-type dopant. Thequantum dots may each have a core-shell structure. In such core-shellstructure, any appropriate functional layer (a single layer or aplurality of layers) may be formed around a shell in accordance with apurpose, and the surface of the shell may be subjected to a surfacetreatment and/or chemical modification.

Any appropriate shape may be adopted as the shape of each of the quantumdots in accordance with a purpose. Specific examples of the shape ofeach of the quantum dots include a perfect spherical shape, a flakyshape, a plate shape, an elliptical spherical shape, and an indefiniteshape.

Any appropriate size may be adopted as the size of the quantum dots inaccordance with a desired emission wavelength. The size of the quantumdots is preferably from 1 nm to 10 nm, more preferably from 2 nm to 8nm. When the size of the quantum dots falls within such ranges, greenlight emission and red light emission each become sharp, and hence ahigh color rendering property can be achieved. For example, green lightmay be emitted when the size of the quantum dots is about 7 nm, and redlight may be emitted when the size is about 3 nm. For example, when theshape of each of the quantum dots is a perfect spherical shape, the sizeof the quantum dots is their average particle diameter, and when theshape is a shape except the perfect spherical shape, the size is adimension along the minimum axis in the shape.

The quantum dots are described in detail in, for example, JP 2012-169271A, JP 2015-102857 A, JP 2015-65158 A, JP 2013-544018 A, and JP2010-533976 A, the descriptions of which are incorporated herein byreference. Commercial products may be used as the quantum dots.

(Phosphor)

Any appropriate phosphor capable of emitting light having a desiredcolor maybe used as the phosphor in accordance with a purpose. Specificexamples thereof include a red phosphor and a green phosphor.

The red phosphor is, for example, a composite fluoride phosphoractivated with Mn⁴⁺. The composite fluoride phosphor refers to acoordination compound that contains at least one coordination center(e.g., M to be described later), that is surrounded with fluoride ionseach acting as a ligand, and that is compensated with charge by acounterion (e.g., A to be described later) as required. Specificexamples of such composite fluoride phosphor include A₂[MF₅]:Mn⁴⁺,A₃[MF₆]:Mn⁴⁺, Zn₂[MF₇]:Mn⁴⁺, A[In₂F₇]:Mn⁴⁺, A₂[M′F₆]:Mn⁴⁺, E[M′F₆]:Mn⁴⁺,A₃[ZrF₇]:Mn⁴⁺, and Ba_(0.65)Zr_(0.35)F_(2.70):Mn⁴⁺. Herein, A representsLi, Na, K, Rb, Cs, NH₄, or a combination thereof. M represents Al, Ga,In, or a combination thereof. M′ represents Ge, Si, Sn, Ti, Zr, or acombination thereof. E represents Mg, Ca, Sr, Ba, Zn, or a combinationthereof. Such a composite fluoride phosphor that a coordination numberin its coordination center is 6 is preferred. Details about such redphosphor are described in, for example, JP 2015-84327 A, the descriptionof which is incorporated herein by reference in its entirety.

The green phosphor is, for example, a compound containing, as a maincomponent, a solid solution of a sialon having a β-type Si₃N₄ crystalstructure. A treatment for setting the amount of oxygen in such sialoncrystal to a specific amount (e.g., 0.8 mass %) or less is preferablyperformed. The performance of such treatment can provide a greenphosphor that emits sharp light having a narrow peak width. Detailsabout such green phosphor are described in, for example, JP2013-28814A,the description of which is incorporated herein by reference in itsentirety.

<<Absorption Layer>>

The absorption layer preferably contains any appropriate one or morekinds of coloring materials. In the absorption layer, the coloringmaterial is typically present in a matrix.

As described above, the absorption layer has an absorption peak in thewavelength band in the range of from 580 nm to 610 nm. The formation ofsuch absorption layer can improve the antireflection function of theoptical laminate while suppressing a reduction in visible lighttransmittance (i.e., a reduction in brightness) thereof. In addition,when the wavelength of light to be absorbed by the layer is adjusted, areflection hue can be made neutral, and hence an optical laminatereduced in coloring can be obtained. The absorption spectrum of thelayer maybe measured with a spectrophotometer (manufactured by HitachiHigh-Technologies Corporation, product name: “U-4100”).

The ratio (A₅₄₅/A_(max)) of the absorbance A₅₄₅ of the peak of theabsorption layer at a wavelength of 545 nm to the absorbance A_(max) ofthe highest absorption peak of the absorption layer at a wavelength offrom 580 nm to 610 nm is preferably 0.13 or less, more preferably 0.12or less, still more preferably 0.11 or less, particularly preferably 0.1or less. When an absorption layer having a small absorbance at awavelength of 545 nm as described above is formed, an optical laminatethat can contribute to the widening of the color gamut of an imagedisplay apparatus by absorbing light that is not needed for colorrepresentation can be obtained. In addition, the layer hardly absorbslight emitted from a light source whose wavelength is around 545 nm atwhich a visibility is high, and hence can be suppressed in brightnessreduction.

In the absorption layer, the half width of the absorption peak in thewavelength range of from 580 nm to 610 nm is preferably 35 nm or less,more preferably 30 nm or less, still more preferably 25 nm or less,particularly preferably 20 nm or less. When the half width falls withinsuch ranges, an optical laminate that can contribute to the widening ofthe color gamut of an image display apparatus can be obtained.

In one embodiment, the absorption layer is free of an absorption peak inthe range of from 530 nm to 570 nm. More specifically, the absorptionlayer is free of an absorption peak having an absorbance of 0.1 or morein the range of from 530 nm to 570 nm. The formation of such absorptionlayer can provide an optical laminate that can contribute to thewidening of the color gamut of an image display apparatus.

In one embodiment, the absorption layer further has an absorption peakin a wavelength band in the range of from 440 nm to 510 nm. That is, inthis embodiment, the absorption layer has absorption peaks in thewavelength bands in the ranges of from 440 nm to 510 nm and from 580 nmto 610 nm. With such configuration, the color mixing of red light andgreen light, and that of green light and blue light can besatisfactorily prevented. When the optical laminate configured asdescribed above is used as an antireflection film for an image displayapparatus, the color gamut of the image display apparatus can bewidened, and hence bright and vivid image quality can be obtained. Anabsorption layer having two or more absorption peaks as described abovemay be obtained by using a plurality of kinds of coloring materials.

The transmittance of the absorption layer at an absorption peak ispreferably from 0% to 80%, more preferably from 0% to 70%. When thetransmittance falls within such ranges, the above-mentioned effect ofthe present invention becomes more significant.

The visible light transmittance of the absorption layer is preferablyfrom 30% to 90%, more preferably from 30% to 80%. When the visible lighttransmittance falls within such ranges, an optical laminate that canexhibit an antireflection function while being suppressed in brightnessreduction can be obtained.

The haze value of the absorption layer is preferably 15% or less, morepreferably 10% or less, still more preferably 5% or less. Although thehaze value of the absorption layer is preferably as small as possible,its lower limit is, for example, 0.1%.

The thickness of the absorption layer is preferably from 1 μm to 100 μm,more preferably from 2 μm to 30 μm.

(Coloring Material)

In one embodiment, the absorption layer contains, as a coloringmaterial, a compound X represented by the following general formula (I)or general formula (II). The compound X is a compound having anabsorption peak in the wavelength band in the range of from 580 nm to610 nm.

in the formula (I),

R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, a substituted or unsubstituted alkylgroup having 1 or more and 20 or less carbon atoms, a substituentrepresented by the formula (a), or a substituent represented by theformula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₃, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₄, R₅, R₆, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₅ and R₆ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₁, R₂, R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₆ and R₇ form a saturated cyclic skeleton including 5 to 7 carbonatoms, and R₁, R₂, R₃, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b),

R₁ and R₂ form a saturated cyclic skeleton including 5 or 6 carbonatoms, R₅ and R₆ form a saturated cyclic skeleton including 5 or 6carbon atoms, and R₃, R₄, R₇, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b), or

R₂ and R₃ form a saturated cyclic skeleton including 5 to 7 carbonatoms, R₆ and R₇ form a saturated cyclic skeleton including 5 to 7carbon atoms, and R₁, R₄, R₅, and R₈ each independently represent ahydrogen atom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b); and

in the formula (II), R₄ and R₈ each independently represent a hydrogenatom, or a substituted or unsubstituted alkyl group having 1 or more and20 or less carbon atoms.

The saturated cyclic skeleton (number of carbon atoms: 5 or 6) formed soas to include R₁ and R₂, and the saturated cyclic skeleton (number ofcarbon atoms: 5 or 6) formed so as to include R₅ and R₆ may each have asubstituent. The substituent is, for example, an alkyl group having 1 to4 carbon atoms. In addition, the saturated cyclic skeleton (number ofcarbon atoms: 5 to 7) formed so as to include R₂ and R₃, and thesaturated cyclic skeleton (number of carbon atoms: 5 to 7) formed so asto include R₆ and R₇ may each have a substituent. The substituent is,for example, an alkyl group having 1 to 4 carbon atoms.

In one embodiment, R₄ and/or R₈ has a benzene ring or a naphthalene ringas a substituent.

Specific examples of the compound X represented by the formula (I) or(II) include compounds represented by the following general formulae(I-1) to (I-27) and (II-1). The absorption peak of the compound X isshown in each of the following tables. With regard to each of theformulae (I-1) to (I-23), an absorption peak obtained by measuring theabsorbance of a film formed of a resin composition prepared by mixingaliphatic polycarbonate with the compound X is shown, and with regard toeach of the formulae (I-24) to (I-27) and (II-1), an absorption peakobtained by measuring the absorbance of a film formed of a resincomposition prepared by mixing a polymethyl methacrylate resin with thecompound X is shown.

Absorption peak NO. Compound X (nm) I-1

596 nm (APC) I-2

595 nm (APC) I-3

582 nm (APC) I-4

585 nm (APC) I-5

585 nm (APC) I-6

575 nm (APC) I-7

585 nm (APC) I-8

587 nm (APC) I-9

587 nm (APC) I-10

588 nm (APC) I-11

588 nm (APC) I-12

589 nm (APC) I-13

592 nm (APC) I-14

591 nm (APC) I-15

595 nm (APC) I-16

595 nm (APC) I-17

596 nm (APC) I-18

614 nm (APC) I-19

581 nm (APC) I-20

591 nm (APC) I-21

593 nm (APC) I-22

594 nm (APC) I-23

594 nm (APC) I-24

592 nm I-25

593 nm I-26

594 nm I-27

594 nm II-1

597 nm

The content of the compound X is preferably from 0.01 part by weight to50 parts by weight, more preferably from 0.05 part by weight to 10 partsby weight, still more preferably from 0.1 part by weight to 5 parts byweight, particularly preferably from 0.1 part by weight to 1 part byweight with respect to 100 parts by weight of the matrix material.

The absorption layer may further contain a compound having an absorptionpeak in the wavelength band in the range of from 440 nm to 510 nm. Forexample, an anthraquinone-based, oxime-based, naphthoquinone-based,quinizarin-based, oxonol-based, azo-based, xanthene-based, orphthalocyanine-based compound (dye) is used as such compound.

The content of the compound having an absorption peak in the wavelengthband in the range of from 440 nm to 510 nm is preferably from 0.01 partby weight to 50 parts by weight, more preferably from 0.01 part byweight to 25 parts by weight with respect to 100 parts by weight of thematrix material.

(Matrix)

The matrix may be a pressure-sensitive adhesive, or may be a resin film.The matrix is preferably a pressure-sensitive adhesive. In addition, thefollowing may be performed: an absorption layer is formed by using theresin film, and the absorption layer is used as a functional layer, suchas a hard coat layer (or as one component of the functional layer).

When the matrix is a pressure-sensitive adhesive, any appropriatepressure-sensitive adhesive may be used as the pressure-sensitiveadhesive to the extent that the effect of the present invention is notimpaired. The pressure-sensitive adhesive preferably has transparencyand optical isotropy. Specific examples of the pressure-sensitiveadhesive include a rubber-based pressure-sensitive adhesive, an acrylicpressure-sensitive adhesive, a silicone-based pressure-sensitiveadhesive, an epoxy-based pressure-sensitive adhesive, and acellulose-based pressure-sensitive adhesive. The pressure-sensitiveadhesive is preferably a rubber-based pressure-sensitive adhesive or anacrylic pressure-sensitive adhesive.

A rubber-based polymer serving as the rubber-based pressure-sensitiveadhesive is a polymer showing rubber elasticity in a temperature regionaround room temperature. Preferred examples of the rubber-based polymer(A) include a styrene-based thermoplastic elastomer (A1), anisobutylene-based polymer (A2), and a combination thereof.

Examples of the styrene-based thermoplastic elastomer (A1) may includestyrene-based block copolymers, such as astyrene-ethylene-butylene-styrene block copolymer (SEBS), astyrene-isoprene-styrene block copolymer (SIS), astyrene-butadiene-styrene block copolymer (SBS), astyrene-ethylene-propylene-styrene block copolymer (SEPS, a hydrogenatedproduct of SIS), a styrene-ethylene-propylene block copolymer (SEP, ahydrogenated product of a styrene-isoprene block copolymer), astyrene-isobutylene-styrene block copolymer (SIBS), and astyrene-butadiene rubber (SBR). Of those, astyrene-ethylene-propylene-styrene block copolymer (SEPS, a hydrogenatedproduct of SIS), a styrene-ethylene-butylene-styrene block copolymer(SEBS), and a styrene-isobutylene-styrene block copolymer (SIBS) arepreferred because the copolymers each have polystyrene blocks at bothends of a molecule thereof and have a high cohesive force as a polymer.A commercial product may be used as the styrene-based thermoplasticelastomer (Al). Specific examples of the commercial product includeSEPTON and HYBRAR manufactured by Kuraray Co., Ltd., Tuftec manufacturedby Asahi Kasei Chemicals Corporation, and SIBSTAR manufactured by KanekaCorporation.

The weight-average molecular weight of the styrene-based thermoplasticelastomer (A1) is preferably from about 50,000 to about 500,000, morepreferably from about 50,000 to about 300,000, still more preferablyfrom about 50,000 to about 250,000. The weight-average molecular weightof the styrene-based thermoplastic elastomer (A1) preferably fallswithin such ranges because both of the cohesive force andviscoelasticity of the polymer can be achieved.

A styrene content in the styrene-based thermoplastic elastomer (A1) ispreferably from about 5 wt % to about 70 wt %, more preferably fromabout 5 wt % to about 40 wt %, still more preferably from about 10 wt %to about 20 wt %. The styrene content in the styrene-based thermoplasticelastomer (A1) preferably falls within such ranges becauseviscoelasticity based on a soft segment can be secured while a cohesiveforce based on a styrene moiety is maintained.

Examples of the isobutylene-based polymer (A2) may include polymers eachincluding isobutylene as a constituent monomer and having aweight-average molecular weight (Mw) of preferably 500,000 or more. Theisobutylene-based polymer (A2) may be a homopolymer of isobutylene(polyisobutylene, PIB) or may be a copolymer including isobutylene as amain monomer (i.e., a copolymer obtained by copolymerizing isobutyleneat a ratio of more than 50 mol %). Examples of such copolymer mayinclude a copolymer of isobutylene and normal butylene, a copolymer ofisobutylene and isoprene (e.g., a butyl rubber, such as a regular butylrubber, a chlorinated butyl rubber, a brominated butyl rubber, or apartially cross-linked butyl rubber), and vulcanized products andmodified products thereof (e.g., a product modified with a functionalgroup, such as a hydroxyl group, a carboxyl group, an amino group, or anepoxy group). Of those, polyisobutylene (PIB) is preferred because thepolyisobutylene is free of a double bond in its main chain, and isexcellent in weatherability. A commercial product may be used as theisobutylene-based polymer (A2). The commercial product is specifically,for example, OPPANOL manufactured by BASF.

The weight-average molecular weight (Mw) of the isobutylene-basedpolymer (A2) is preferably 500,000 or more, more preferably 600,000 ormore, still more preferably 700,000 or more. In addition, the upperlimit of the weight-average molecular weight (Mw) is preferably5,000,000 or less, more preferably 3,000,000 or less, still morepreferably 2,000,000 or less. When the weight-average molecular weightof the isobutylene-based polymer (A2) is set to 500,000 or more, apressure-sensitive adhesive that is more excellent in durability at thetime of its high-temperature storage can be obtained.

The content of the rubber-based polymer (A) in the pressure-sensitiveadhesive is preferably 30 wt % or more, more preferably 40 wt % or more,still more preferably 50 wt % or more, particularly preferably 60 wt %or more in the total solid content of the pressure-sensitive adhesive.The upper limit of the content of the rubber-based polymer is preferably95 wt % or less, more preferably 90 wt % or less.

In the rubber-based pressure-sensitive adhesive, the rubber-basedpolymer (A) and any other rubber-based polymer may be used incombination. Specific examples of the other rubber-based polymerinclude: a butyl rubber (IIR), a butadiene rubber (BR), anacrylonitrile-butadiene rubber (NBR), EPR (binary ethylene-propylenerubber), EPT (ternary ethylene-propylene rubber), an acrylic rubber, aurethane rubber, and a polyurethane-based thermoplastic elastomer; apolyester-based thermoplastic elastomer; and a blend-based thermoplasticelastomer, such as a polymer blend of polypropylene and EPT (ternaryethylene-propylene rubber). The compounding amount of the otherrubber-based polymer is preferably about 10 parts by weight or less withrespect to 100 parts by weight of the rubber-based polymer (A).

The acrylic polymer of the acrylic pressure-sensitive adhesive typicallycontains an alkyl (meth)acrylate as a main component, and may contain anaromatic ring-containing (meth)acrylate, an amide group-containingmonomer, a carboxyl group-containing monomer, and/or a hydroxylgroup-containing monomer as a copolymerization component in accordancewith a purpose. The term “(meth)acrylate” as used herein means anacrylate and/or a methacrylate. The alkyl (meth)acrylate may be, forexample, an alkyl (meth) acrylate having a linear or branched alkylgroup having 1 to 18 carbon atoms. The aromatic ring-containing(meth)acrylate is a compound containing an aromatic ring structure inits structure and containing a (meth)acryloyl group. The aromatic ringis, for example, a benzene ring, a naphthalene ring, or a biphenyl ring.The aromatic ring-containing (meth)acrylate satisfies durability and canalleviate display unevenness due to a white void of the peripheralportion of an image display apparatus. The amide group-containingmonomer is a compound containing an amide group in its structure andcontaining a polymerizable unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. The carboxyl group-containing monomeris a compound containing a carboxyl group in its structure andcontaining a polymerizable unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. The hydroxyl group-containing monomeris a compound containing a hydroxyl group in its structure andcontaining a polymerizable unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. Details about the acrylicpressure-sensitive adhesive are described in, for example, JP2015-199942 A, the description of which is incorporated herein byreference.

When the matrix is a resin film, any appropriate resin may be used as aresin for forming the resin film. Specifically, the resin may be athermoplastic resin, may be a thermosetting resin, or may be an activeenergy ray-curable resin. Examples of the active energy ray-curableresin include an electron beam-curable resin, a UV-curable resin, and avisible light-curable resin.

When the matrix is a resin film, specific examples of the resin forforming the resin film include epoxy, (meth)acrylates (e.g., methylmethacrylate and butyl acrylate), norbornene, polyethylene, poly(vinylbutyral), poly(vinyl acetate), polyurea, polyurethane, aminosilicone(AMS), polyphenylmethylsiloxane, polyphenylalkylsiloxanes,polydiphenylsiloxane, polydialkylsiloxanes, silsesquioxanes, siliconefluoride, vinyl and hydride-substituted silicones, styrene-basedpolymers (e.g., polystyrene, aminopolystyrene (APS), poly(acrylonitrileethylene styrene) (AES)), polymers each cross-linked with a difunctionalmonomer (e.g., divinylbenzene), polyester-based polymers (e.g.,polyethylene terephthalate), cellulose-based polymers (e.g., triacetylcellulose), vinyl chloride-based polymers, amide-based polymers,imide-based polymers, vinyl alcohol-based polymers, epoxy-basedpolymers, silicone-based polymers, and acrylic urethane-based polymers.Those resins may be used alone or in combination thereof (e.g., blend orcopolymer). After any one of those resins has been formed into a film,the film may be subjected to a treatment, such as stretching, heating,or pressurization. The resin is preferably a thermosetting resin or aUV-curable resin, more preferably a thermosetting resin.

<<Protective Film>>

Any appropriate film may be used as the protective film. Specificexamples of a material serving as a main component of such film includetransparent resins, such as a cellulose-based resin, such as triacetylcellulose (TAC), a (meth)acrylic resin, a polyester-based resin, apolyvinyl alcohol-based resin, a polycarbonate-based resin, apolyamide-based resin, a polyimide-based resin, a polyethersulfone-based resin, a polysulfone-based resin, a polystyrene-basedresin, a polynorbornene-based resin, a polyolefin-based resin, and anacetate-based resin. In addition, the examples also includethermosetting resins or UV-curable resins, such as an acrylic resin, aurethane-based resin, an acrylic urethane-based resin, an epoxy-basedresin, and a silicone-based resin. In addition to the foregoing, aglassy polymer, such as a siloxane-based polymer, is also given as anexample. A polymer film described in JP 2001-343529 A (WO 01/37007 A1)may also be used. For example, a resin composition containing athermoplastic resin having a substituted or unsubstituted imide group ina side chain thereof, and a thermoplastic resin having a substituted orunsubstituted phenyl group and a nitrile group in side chains thereofmaybe used as a material for the film, and the resin composition is, forexample, a resin composition including: an alternating copolymer formedof isobutene and N-methylmaleimide; and an acrylonitrile-styrenecopolymer. The polymer film may be, for example, an extrusion moldedproduct of the resin composition. Any appropriate pressure-sensitiveadhesive layer or adhesive layer is used in the lamination of apolarizer and the protective film. The pressure-sensitive adhesive layeris typically formed of an acrylic pressure-sensitive adhesive. Theadhesive layer is typically formed of a polyvinyl alcohol-basedadhesive.

<<Refractive Index-Adjusting Layer>>

The refractive index of the refractive index-adjusting layer ispreferably 1.2 or less, more preferably 1.15 or less, still morepreferably from 1.01 to 1.1. When the refractive index of the refractiveindex-adjusting layer falls within such ranges, the utilizationefficiency of light output from the wavelength conversion layer can beimproved, and ambient light reflection can be suppressed.

The refractive index-adjusting layer typically has a void therein. Thevoid content of the refractive index-adjusting layer may adopt anyappropriate value. The void content of the refractive index-adjustinglayer is preferably from 5% to 99%, more preferably from 25% to 95%.When the void content of the refractive index-adjusting layer fallswithin such ranges, the refractive index of the refractiveindex-adjusting layer can be sufficiently reduced, and the layer canobtain high mechanical strength.

The refractive index-adjusting layer having a void therein maybe formedof, for example, a structure having at least one shape selected from aparticulate shape, a fibrous shape, and a flat plate shape. A structure(constituent unit) for forming the particulate shape may be a solidparticle or a hollow particle, and specific examples thereof include:silicone particles and silicone particles each having a fine pore; andsilica hollow nanoparticles and silica hollow nanoballoons. A fibrousconstituent unit is, for example, a nanofiber having a nanosizeddiameter, and specific examples thereof include cellulose nanofibers andalumina nanofibers. A flat plate-shaped constituent unit is, forexample, nanoclay, and is specifically, for example, nanosized bentonite(e.g., KUNIPIA F (product name)).

Any appropriate material may be adopted as a material for forming therefractive index-adjusting layer. Materials described in, for example,WO 2004/113966 A1, JP 2013-254183 A, and JP 2012-189802 A may each beadopted as such material. Specific examples thereof include:silica-based compounds; hydrolyzable silanes, and partial hydrolysatesand dehydration condensates thereof; organic polymers; silanolgroup-containing silicon compounds; active silicas each obtained bybringing a silicate into contact with an acid or an ion-exchange resin;polymerizable monomers (e.g., a (meth) acrylic monomer and astyrene-based monomer); curable resins (e.g., a (meth)acrylic resin, afluorine-containing resin, and a urethane resin); and combinationsthereof.

Examples of the organic polymer include polyolefins (e.g., polyethyleneand polypropylene), polyurethanes, fluorine-containing polymers (e.g., afluorine-containing copolymer having a fluorine-containing monomer unitand a constituent unit for imparting cross-linking reactivity asconstituent components), polyesters (e.g., a poly(meth)acrylic acidderivative (the term “(meth)acrylic acid” as used herein means acrylicacid and methacrylic acid, and “(meth)” is used in such meaning in allcases)), polyethers, polyamides, polyimides, polyureas, andpolycarbonates.

The material for forming the refractive index-adjusting layer preferablyincludes: silica-based compounds; and hydrolyzable silanes, and partialhydrolysates and dehydration condensates thereof.

Examples of the silica-based compound include: SiO₂ (silicic anhydride); and compounds each containing SiO₂ and at least one compound selectedfrom the group consisting of Na₂O—B₂O₃ (borosilicic acid), Al₂O₃(alumina), B₂O₃, TiO₂, ZrO₂, SnO₂, Ce₂O₃, P₂O₅, Sb₂O₃, MoO₃, ZnO₂, WO₃,TiO₂—Al₂O₃, TiO₂—ZrO₂, In₂O₃—SnO₂, and Sb₂O₃—SnO₂ (the symbol “—”indicates that the oxide is a composite oxide).

The hydrolyzable silanes are, for example, hydrolyzable silanes eachcontaining an alkyl group that may have a substituent (e.g., fluorine).The hydrolyzable silanes, and the partial hydrolysates and dehydrationcondensates thereof are preferably an alkoxysilane and a silsesquioxane.

The alkoxysilane may be a monomer or an oligomer. The alkoxysilanemonomer preferably has three or more alkoxyl groups. Examples of thealkoxysilane monomer include methyltrimethoxysilane,methyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane,tetraethoxysilane, tetrabutoxysilane, tetrapropoxysilane,diethoxydimethoxysilane, dimethyldimethoxysilane, anddimethyldiethoxysilane. The alkoxysilane oligomer is preferably apolycondensate obtained by subjecting the alkoxysilane monomer tohydrolysis and polycondensation. When the alkoxysilane is used as thematerial for forming the refractive index-adjusting layer, a refractiveindex-adjusting layer having excellent uniformity is obtained.

The silsesquioxane is a collective term of network-like polysiloxaneseach represented by the general formula RSiO_(1.5) (provided that Rrepresents an organic functional group). Examples of the organicfunctional group represented by R include an alkyl group (the group maybe linear or branched, and has 1 to 6 carbon atoms), a phenyl group, andan alkoxy group (e.g., a methoxy group and an ethoxy group). Thesilsesquioxane has, for example, any one of a ladder-type structure anda cage-type structure. When the silsesquioxane is used as theabove-mentioned material, a refractive index-adjusting layer havingexcellent uniformity, excellent weatherability, excellent transparency,and excellent hardness is obtained.

Any appropriate particles may be adopted as the above-mentionedparticles. The particles are typically silica particles.

The shape of each of the silica particles may be identified through, forexample, observation with a transmission electron microscope. Theaverage particle diameter of the silica particles is preferably from 5nm to 200 nm, more preferably from 10 nm to 200 nm. When the particleshave such configuration, a refractive index-adjusting layer having asufficiently low refractive index can be obtained, and the transparencyof the refractive index-adjusting layer can be maintained. In thisdescription, the average particle diameter means a value given from thespecific surface area (m²/g) of the particles, which is measured by anitrogen adsorption method (BET method),by the equation “averageparticle diameter=(2,720/specific surface area)” (see JP 01-317115 A).

Examples of a method of obtaining the refractive index-adjusting layerinclude methods described in JP 2010-189212 A, JP 2008-040171 A, JP2006-011175 A, WO 2004/113966 A1, and references thereof. Specificexamples thereof include: a method including subjecting at least one ofa silica-based compound, and hydrolyzable silanes, and partialhydrolysates and dehydration condensates thereof to hydrolysis andpolycondensation; a method including using porous particles and/orhollow fine particles; a method including producing an aerogel layerthrough the utilization of a springback phenomenon; and a methodincluding using pulverized gel, which is obtained by pulverizing gelobtained through a sol-gel process and chemically bonding fine porousparticles in the pulverization liquid with a catalyst or the like.However, the method of obtaining the refractive index-adjusting layer isnot limited to the production methods, and the layer may be produced byany production method.

The refractive index-adjusting layer may be bonded to the wavelengthconversion layer or the absorption layer via any appropriate adhesionlayer (e.g., an adhesive layer or a pressure-sensitive adhesive layer:not shown). When the refractive index-adjusting layer includes apressure-sensitive adhesive, the adhesion layer may be omitted.

The haze of the refractive index-adjusting layer is, for example, from0.1% to 30%, preferably from 0.2% to 10%.

With regard to the mechanical strength of the refractive index-adjustinglayer, for example, its scratch resistance against BEMCOT (trademark) isdesirably from 60% to 100%.

An anchoring force between the refractive index-adjusting layer and thewavelength conversion layer or the absorption layer, which is notparticularly limited, is preferably 0.01 N/25 mm or more, morepreferably 0.1 N/25 mm or more, still more preferably 1 N/25 mm or more.To improve the mechanical strength or the anchoring force, therefractive index-adjusting layer may be subjected to an undercoatingtreatment, a heating treatment, a humidifying treatment, a UV treatment,a corona treatment, a plasma treatment, or the like in a step before orafter the formation of its coating film, or before or after its bondingto any appropriate adhesion layer or any other member.

The thickness of the refractive index-adjusting layer is preferably from100 nm to 5,000 nm, more preferably from 200 nm to 4,000 nm, still morepreferably from 300 nm to 3,000 nm, particularly preferably from 500 nmto 2,000 nm. When the thickness falls within such ranges, a refractiveindex-adjusting layer, which expresses an optically sufficient functionon light in a visible light region, and which has excellent durability,can be achieved.

<<<<Image Display Apparatus>>>>

FIG. 2 is a schematic sectional view of one embodiment of an imagedisplay apparatus including the optical laminate of the presentinvention. In FIG. 2, a case in which the image display apparatus is aliquid crystal display apparatus is illustrated as a typical example. Aliquid crystal display apparatus 1000 includes a liquid crystal panel200 and a backlight 300, and the optical laminate of the presentinvention may be a member for the liquid crystal panel 200. Thewavelength conversion layer may be a color filter to be included in theliquid crystal panel 200.

In one embodiment, the optical laminate is an optical laminate includinga wavelength conversion layer and an absorption layer, and is free of apolarizing plate on the side of the absorption layer opposite to thewavelength conversion layer. One embodiment of such optical laminate ofthe present invention includes the absorption layer 20, the wavelengthconversion layer 10, and a polarizing plate 30 in the stated order asillustrated in, for example, FIG. 3. In FIG. 3, typically, theabsorption layer 20 side is a viewer side, and the polarizing plate 30side is a backlight side. Of course, FIG. 3 is merely one embodiment ofthe optical laminate of the present invention, and the optical laminateof the present invention is not limited to the embodiment illustrated inFIG. 3.

More specifically, the liquid crystal display apparatus 1000 may adopt,for example, such an embodiment as illustrated in FIG. 4. In FIG. 4, theliquid crystal display apparatus 1000 includes the liquid crystal panel200 and the backlight 300, and the liquid crystal panel 200 includes theabsorption layer 20, the wavelength conversion layer 10, a polarizingplate (viewer-side polarizing plate) 30 a, a liquid crystal cell 40, anda polarizing plate (backlight-side polarizing plate) 30 b in the statedorder. In FIG. 4, the absorption layer 20 side is a viewer side, and thepolarizing plate (backlight-side polarizing plate) 30 b side is abacklight side. Of course, FIG. 4 is merely one embodiment of the imagedisplay apparatus including the optical laminate of the presentinvention, and the image display apparatus including the opticallaminate of the present invention is not limited to the embodimentillustrated in FIG. 4.

A light source to be included in the backlight is, for example, acold-cathode tube light source (CCFL) or a LED light source. In oneembodiment, the backlight includes the LED light source. The use of theLED light source can provide an image display apparatus excellent inviewing angle characteristic. In one embodiment, a light source(preferably a LED light source) configured to emit blue light is used.

The backlight may be of a direct system, or may be of an edge lightsystem.

The backlight may further include any other member, such as a lightguide plate, a diffusion plate, or a prism sheet, in addition to thelight source as required.

The liquid crystal panel typically includes the liquid crystal cell.

The liquid crystal cell includes a pair of substrates and a liquidcrystal layer serving as a display medium, the layer being sandwichedbetween the substrates. Ina general configuration, a color filter (e.g.,a wavelength conversion layer) and a black matrix are arranged on onesubstrate, and a switching element configured to control theelectro-optical characteristics of the liquid crystal, a scan lineconfigured to apply a gate signal to the switching element and a signalline configured to apply a source signal thereto, and a pixel electrodeand a counter electrode are arranged on the other substrate. An interval(cell gap) between the substrates may be controlled with, for example, aspacer. For example, an alignment film formed of polyimide may bearranged on the side of each of the substrates in contact with theliquid crystal layer.

In one embodiment, the liquid crystal layer contains liquid crystalmolecules aligned in homeotropic alignment under a state in which noelectric field is present. Such liquid crystal layer (as a result, theliquid crystal cell) typically shows a three-dimensional refractiveindex of nz>nx=ny. A drive mode using the liquid crystal moleculesaligned in homeotropic alignment under a state in which no electricfield is present is, for example, a vertical alignment (VA) mode. The VAmode encompasses a multi-domain VA (MVA) mode.

In another embodiment, the liquid crystal layer contains liquid crystalmolecules aligned in homogeneous alignment under a state in which noelectric field is present. Such liquid crystal layer (as a result, theliquid crystal cell) typically shows a three-dimensional refractiveindex of nx>ny=nz. The relationship “ny=nz” as used herein encompassesnot only a case in which the ny and the nz are completely equal to eachother, but also a case in which the ny and the nz are substantiallyequal to each other. Typical examples of a drive mode using the liquidcrystal layer that shows such three-dimensional refractive index includean in-plane switching (IPS) mode and a fringe field switching (FFS)mode. The above-mentioned IPS mode encompasses a super in-planeswitching (S-IPS) mode or an advanced super in-plane switching (AS-IPS)mode, which adopts, for example, a V-shaped electrode or a zigzagelectrode. In addition, the above-mentioned FFS mode encompasses anadvanced fringe field switching (A-FFS) mode or an ultra fringe fieldswitching (U-FFS) mode, which adopts, for example, a V-shaped electrodeor a zigzag electrode. The symbol “nx” represents a refractive index inthe direction in which a refractive index in a plane becomes maximum(i.e., a slow axis direction), the symbol “ny” represents a refractiveindex in the direction perpendicular to the slow axis in the plane(i.e., a fast axis direction), and the symbol “nz” represents athickness direction refractive index.

EXAMPLES

Now, the present invention is specifically described by way of Examples.However, the present invention is by no means limited by these Examples.Methods of measuring the respective characteristics are as describedbelow.

[Reflectance, Reflection Spectrum, and Reflection Hue (a*, b*)]

The total light reflectance, reflection spectrum, and reflection hue(a*, b*) of an optical laminate obtained in each of Example andComparative Examples were measured with a spectrocolorimeter CM-2600d(light source: D65) manufactured by Konica Minolta, Inc. In the case ofan optical laminate including a wavelength conversion layer and anabsorption layer, a reflective plate (manufactured by Toray AdvancedFilm Co., Ltd., CERAPEEL DMS-X42) was bonded to a wavelength conversionlayer side via an acrylic pressure-sensitive adhesive (thickness: 20 μm)produced with reference to JP 2549388 B2, and light was caused to enterfrom an absorption layer side.

[Δab]

A Δab was determined from the reflection hue (a*, b*) by using theequation “Δab=(a*²+b*²)^(1/2)”.

[Front Brightness]

The optical laminate obtained in each of Example and ComparativeExamples was arranged so that its wavelength conversion layer was on alight source side, and its brightness was measured with a brightnessmeter (manufactured by Konica Minolta, Inc., product name: “SR-UL1”) byusing blue LED uniform light-emitting surface lighting (manufactured byAitec System Co., Ltd.: model number: TMN150X180-22BD-4) as a lightsource. The luminous brightness of the uniform light-emitting surfacelighting was 1, 335 cd/m² in the case of the wavelength conversion layeralone.

Example 1 (Wavelength Conversion Layer)

A commercial television (manufactured by Samsung Electronics Co., Ltd.,product name: “UN65JS9000FXZA”) was dismantled to provide a wavelengthconversion material in its backlight side, that is, a quantum dot sheet.The quantum dot sheet was adopted as a wavelength conversion layer (1).

(Absorption Layer)

A coloring matter-containing pressure-sensitive adhesive containing 0.3part by weight of a radical generator (benzoyl peroxide, manufactured byNippon Oil & Fats Co., Ltd., product name: “NYPER BMT”), 1 part byweight of an isocyanate-based cross-linking agent (manufactured by TosohCorporation, product name: “CORONATE L”), 0.3 part by weight of asquaraine compound represented by the following general formula (I-20),and 0.2 part by weight of a phenol-based antioxidant (manufactured byBASF Japan Ltd., product name: “IRGANOX 1010”) with respect to 100 partsby weight of an acrylic polymer obtained by copolymerizing n-butylacrylate and a hydroxy group-containing monomer was produced. Thecoloring matter-containing pressure-sensitive adhesive obtained in theforegoing was applied onto a PET substrate (manufactured by MitsubishiPlastics, Inc., product name: “MRF38CK”), which had been subjected to atreatment for facilitating the peeling of the pressure-sensitiveadhesive, with an applicator so as to have a thickness of 20 μm, and theadhesive was dried at 155° C. for 2 minutes. After that, the resultantwas bonded to TAC (triacetyl cellulose film, manufactured by FUJIFILMCorporation). Thus, an absorption layer (1) (absorption maximumwavelength: 594 nm) was formed on the TAC.

The squaraine compound represented by the general formula (I-20) wassynthesized by the following method.

<Synthesis of Squaraine Compound>

1-Phenyl-1,4,5,6-tetrahydrocyclopenta[b]pyrrole was synthesized by amethod described in “M. Beller et. al., J. Am. Chem. Soc., 2013,135(30), 11384-11388”.

300 Milligrams of 1-phenyl-1,4,5,6-tetrahydrocyclopenta[b]pyrrole and 80mg of squaric acid were mixed in 5 mL of ethanol, and the mixture wasstirred at 80° C. for 2 hours. After that, the mixture was cooled toroom temperature, and the product was filtered out. The product that hadbeen filtered out was washed with ethanol, and was dried under reducedpressure at 70° C. to provide 197 mg of a squaraine compound. Further,the compound was purified by silica gel chromatography to provide 120 mgof a squaraine compound.

(Optical Laminate)

The wavelength conversion layer (1) and the absorption layer (1) werelaminated to provide an optical laminate (1) having the laminatedstructure“wavelength conversion layer/absorption layer”. The opticallaminate (1) was subjected to the above-mentioned evaluations. Theresults are shown in Table 1.

Comparative Example 1

An optical laminate (2) including the wavelength conversion layer (1)and an absorption layer (1) (absorption maximum wavelength: 595 nm) wasobtained in the same manner as in Example 1 except that 0.3 part byweight of a porphyrin-based coloring matter (manufactured by YamamotoChemicals, Inc., product name: “PD-320”) was used instead of 0.3 part byweight of the squaraine compound represented by the general formula(I-20). The optical laminate (2) was subjected to the above-mentionedevaluations. The results are shown in Table 1.

Comparative Example 2

An optical laminate (3) was obtained in the same manner as in Example 1except that the coloring matter (squaraine compound) was notincorporated into the pressure-sensitive adhesive for forming theabsorption layer (i.e., a pressure-sensitive adhesive layer was formedinstead of the absorption layer). The optical laminate (3) was subjectedto the above-mentioned evaluations. The results are shown in Table 1.

TABLE 1 Coloring matter a b* Δab Example 1 Squaraine compound −0.96 5.96 Comparative Porphyrin compound −7.7 −2.7 8.2 Example 1 Comparative —−3.8 33 33 Example 2

INDUSTRIAL APPLICABILITY

The optical laminate of the present invention may be suitably utilizedin an image display apparatus.

REFERENCE SIGNS LIST

10 wavelength conversion layer

-   20 absorption layer-   100 optical laminate-   200 liquid crystal panel-   300 backlight-   1000 liquid crystal display apparatus

1. A optical laminate, comprising: a wavelength conversion layer; and anabsorption layer arranged on one side of the wavelength conversionlayer, wherein the absorption layer has an absorption peak in awavelength band in a range of from 580 nm to 610 nm, and wherein theabsorption layer contains a compound X represented by the followinggeneral formula (I) or general formula (II):

in the formula (I), R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈ eachindependently represent a hydrogen atom, a halogen atom, a substitutedor unsubstituted alkyl group having 1 or more and 20 or less carbonatoms, a substituent represented by the formula (a), or a substituentrepresented by the formula (b), R₁ and R₂ form a saturated cyclicskeleton including 5 or 6 carbon atoms, and R₃, R₄, R₅, R₆, R₇, and R₈each independently represent a hydrogen atom, a halogen atom, which ispreferably Cl, a substituted or unsubstituted alkyl group having 1 ormore and 20 or less carbon atoms, a substituent represented by theformula (a), or a substituent represented by the formula (b), R₂ and R₃form a saturated cyclic skeleton including 5 to 7 carbon atoms, and R₁,R₄, R₅, R₆, R₇, and R₈ each independently represent a hydrogen atom, ahalogen atom, which is preferably Cl, a substituted or unsubstitutedalkyl group having 1 or more and 20 or less carbon atoms, a substituentrepresented by the formula (a), or a substituent represented by theformula (b), R₅ and R₆ form a saturated cyclic skeleton including 5 or 6carbon atoms, and R₁, R₂, R₃, R₄, R₇, and R₈ each independentlyrepresent a hydrogen atom, a halogen atom, which is preferably Cl, asubstituted or unsubstituted alkyl group having 1 or more and 20 or lesscarbon atoms, a substituent represented by the formula (a), or asubstituent represented by the formula (b), R₆ and R₇ form a saturatedcyclic skeleton including 5 to 7 carbon atoms, and R₁, R₂, R₃, R₄, R₅,and R₈ each independently represent a hydrogen atom, a halogen atom,which is preferably Cl, a substituted or unsubstituted alkyl grouphaving 1 or more and 20 or less carbon atoms, a substituent representedby the formula (a), or a substituent represented by the formula (b), R₁and R₂ form a saturated cyclic skeleton including 5 or 6 carbon atoms,R₅ and R₆ form a saturated cyclic skeleton including 5 or 6 carbonatoms, and R₃, R₄, R₇, and R₈ each independently represent a hydrogenatom, a halogen atom, which is preferably Cl, a substituted orunsubstituted alkyl group having 1 or more and 20 or less carbon atoms,a substituent represented by the formula (a), or a substituentrepresented by the formula (b), or R₂ and R₃ form a saturated cyclicskeleton including 5 to 7 carbon atoms, R₆ and R₇ form a saturatedcyclic skeleton including 5 to 7 carbon atoms, and R₁, R₄, R₅, and R₈each independently represent a hydrogen atom, a halogen atom, which ispreferably Cl, a substituted or unsubstituted alkyl group having 1 ormore and 20 or less carbon atoms, a substituent represented by theformula (a), or a substituent represented by the formula (b); and in theformula (II), R₄ and R₈ each independently represent a hydrogen atom, ora substituted or unsubstituted alkyl group having 1 or more and 20 orless carbon atoms.
 2. The optical laminate according to claim 1, whereinthe optical laminate is free of a polarizing plate on a side of theabsorption layer opposite to the wavelength conversion layer.
 3. Theoptical laminate according to claim 1, wherein the wavelength conversionlayer contains quantum dots or a phosphor as a wavelength conversionmaterial.
 4. The optical laminate according to claim 1, wherein thewavelength conversion layer is a color filter.
 5. An image displayapparatus, comprising the optical laminate of claim
 1. 6. The imagedisplay apparatus according to claim 5, wherein the image displayapparatus comprises a liquid crystal panel including the opticallaminate of claim 1, and a backlight.
 7. The image display apparatusaccording to claim 6, wherein the liquid crystal panel includes theabsorption layer, the wavelength conversion layer, a viewer-sidepolarizing plate, a liquid crystal cell, and a backlight-side polarizingplate in the stated order from a viewer side.